KR950010981B1 - Foamed Styrene and Styrene Foam - Google Patents

Abstract

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Description

Foamed Styrene and Styrene Foam

The present invention relates to styrene polymer foams having a particularly homogeneous and fine-cell foam structure. The present invention further relates to a foamed styrene polymer, which when foamed provides a particularly homogeneous and fine foam foam.

The production of styrene polymer foams is known. Industrially, a molten styrene polymer is mixed with a blowing agent in an appropriate mixing apparatus under atmospheric pressure or higher to obtain a homogeneous mixture, and passed through a nozzle to foam.

In another industrial method, the styrene polymer to be foamed, ie the styrene polymer containing the blowing agent, is first produced in the form of individual particulates and then heated above the softening point to foam to form a loose pile of foam particles. The foam particles are then further foamed and welded in a perforated internal pressure mold using heated steam to form the foam.

Known styrene polymer foams are susceptible to extreme fluctuations. Until now, it was possible to obtain the required number of bubbles within only a narrow limit. In particular, homogeneous microbubble foam structures have not been satisfactorily realized to date.

We have found that this object can be achieved by adding a small amount of resinic acid or a mixture of lower alkyl esters or (hydro) abiethylphthalates and polyoxyethylene monoesters or monoethers thereof.

Accordingly, the present invention relates to (a) 3 to 15% by weight of a C ₃ -C ₈ hydrocarbon or haloalkane, b) 0.005 to 0.3% by weight of resinic acid, lower alkylesters of resinic acid or (hydro) abiethylphthalate And (c) 0.001 to 0.3 weight percent polyoxyethylene nomoester or monoether, and optionally (d) other conventional additives.

In addition, the present invention has a density of 0.01 to 0.5 g / cm 3 and includes (a) 0.005 to 0.3% by weight of resin acid, lower alkyl ester of resin acid or (hydro) abiethylphthalate and (b) 0.001 to 0.3% by weight. Styrene polymer foams containing polyoxyethylene monoesters or monoethers and optionally (c) conventional additives.

U. S. Patent No. 3,526, 625 also discloses that 0.5-2.5% by weight of resin acids such as (ahydro) abiethic acid or lower alkylesters thereof or (hydro) abiethyl phthalate are used for the preparation of foamed styrene polymers. have. This product has a very low forming temperature when processed into foam. As a result, these foams also have excessively low thermal warpage resistance. Their foam structure is also not satisfactory.

US Pat. No. 3,503,908 discloses that adding 0.15 to 0.28% by weight of polyoxyethylene monoesters or monoethers during the production of foamed styrene polymers reduces mold cooling time when foaming is produced from these polymers. However, the use of these additives results in problems associated with suspension stability and solidification during the manufacture of the foamed styrene polymer. Moreover, the foam structure of the resulting foam is heterogeneous.

Surprisingly, this disadvantage observed when using resinic acids or their lower alkylesters or polyolcyethylene monoesters or monoethers together is avoided when using the two additives in combination according to the invention. Even more surprisingly, this new foam has a structure that is completely homogeneous and that can adjust the number of bubbles as detailed in Examples and Comparative Examples.

For the purposes of the present invention, styrene polymers are polystyrenes and copolymers of styrene with other α, β-olefinically unsaturated compounds (containing at least 50 parts by weight of styrene as units to be copolymerized). Examples of suitable copolymerization components include α-methylstyrene, styrene halogenated in the nucleus, styrene alkylated in the nucleus, acrylonitrile, esters of acrylic or methacrylic acid with alcohols of C ₁ -C ₈ , N- such as vinylcarbazole. There are small amounts of compounds such as vinyl compounds, maleic anhydride or butadiene, divinylbenzene or butanediol diacrylates containing two copolymerizable double bonds. Also suitable are copolymers and graft polymers of 40 to 90 weight percent polystyrene and 10 to 60 weight percent polyethylene or polypropylene.

This foamed styrene polymer is prepared by conventional methods. The polymer may be droplets, cylindrical particles or fragments obtained when the polymer is ground. It is advantageous for the particles to have a diameter of 0.1 to 6 mm, in particular 0.4 to 3 mm.

This styrene polymer contains one or more homogeneously distributed blowing agents. Examples of suitable blowing agents are C ₃ -C ₈ hydrocarbons or halogenated hydrocarbons which are gaseous or liquid at standard pressures and temperatures and do not dissolve the styrene polymer and whose boiling point is lower than the softening point of the polymer. Examples of suitable blowing agents are propane, butane, pentane, cyclopentane, hexane, cyclohexane, octane, dichlorodifluoromethane and trifluorochloromethane. The blowing agent is present in the styrene polymer in an amount of 3 to 15 weight percent, based on the polymer.

An essential feature of the present invention is that the foamed styrene and styrene polymer foams as additives are lower alkylesters of abietinic acid, hydroaviethic acid or their isomers, resinic acid (e.g. methyl, ethyl, propyl, isopropyl, n-, iso-, or tert-butyl ester), abiethyl phthalate or hydroabiethyl phthalate. Mixtures of these materials can also be used. The additive is used in an amount of 0.005 to 0.3, preferably 0.01 to 0.1% by weight, based on the styrene polymer. Also suitable are industrial resin acids, such as (hydro) abietinic acid compounds, and the natural materials that essentially constitute these materials.

Another feature of the invention is that the degree of foaming indicates that the styrene polymer and styrene polymer foam contain polyoxyethylene monoesters or monoethers as another additive. The polyoxyethylene groups of these esters or ethers contain, for example, 3 to 50, preferably 30 to 30, particularly preferably 5 to 25 oxyethylene units. Preferably the esters or ethers are each derived from long chain carboxylic acids and alcohols, in particular they are 6 to 40, preferably 6 to 20 carbon atoms.

Examples of suitable materials include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monopalate, polyoxyethylene monolaurate, polyoxyethylene monosterate, polyoxyethylene mono Lauryl ether, polyoxyethylene monocetyl ether and monooxyethylene monooleyl ether. These materials are used in amounts of 0.001 to 0.3, preferably 0.005 to 0.1% by weight, based on the styrene polymer.

Oxyethylated products of industrial alcohols such as palm oil alcohols are also suitable.

The foamed styrene and styrene foams may also contain other conventional additives that impart certain properties to the article.

Special examples include synergists for organic bromine or chlorine compounds such as tridibromopropyl phosphate, hexabromocyclododecane and chloroparaffins, and for refractory agents such as dicumyl and easily decomposed organic peroxidants, Other antistatic agents, stabilizers, colorants, lubricants, fillers, and materials that have a non-adhesive effect during preforming, such as zinc straight, magnesium sterate, melamine / formaldehyde concentrate or silica. Depending on the intended effect, the additive may be homogeneously dispersed in the particles or present as a surface coating.

Foamed styrene polymers and foams thereof may also contain conventional coatings (eg, glycerol esters such as glycerol distearyl ether) to reduce molding removal time, for example. Particularly advantageous are mixtures of hydroxy carboxylates having glycol esters by weight ratio 5: 1 to 1: 5.

The ester is present as a coating on the surface of the polystyrene particles, at least the major part of which is foamed, and is distributed very homogeneously. The method of treatment is not critical and the finely divided ester can be treated to the styrene polymer particles, for example only by tumbling in a conventional mixer. However, it is also possible to treat the esters from solutions in aqueous acids or organic solvents, the solvent or water having to be removed during the treatment. Moreover, the ester can also be added to the styrene polymer batch at the end or near the end of the suspension polymerization.

Foamed styrene polymers can be produced, for example, by conventional methods of mixing the styrene polymer with blowing agents and additives in a mixing device (eg a compressor). When the melt is extruded into portions under reduced pressure and immediately cooled to prevent the extrudate from expanding, a foamed styrene polymer is obtained. However, the melt can also be foamed into foam immediately after exiting the mixing apparatus. However, it is also possible to impregnate styrene polymers in the form of particles or drops in aqueous suspensions at elevated temperatures with blowing agents and additives in order to produce the product to be foamed.

The foamed styrene polymer is advantageously produced by polymerizing the styrene polymer in an aqueous acid solution in the presence of a blowing agent and additives. After preparation they are present in finely divided forms (eg in the form of drops) and generally have a particle diameter of 0.1 to 6 mm, preferably 0.4 to 3 mm. When they are locked by the conventional method in the pre-foamed state, they are heated in the mold which is not leaking, further foamed, and fired into foam molding corresponding to the cavity of the mold whose dimensions are used.

EXAMPLE

A) Experiment on subsequent impregnation

100 parts complete deionized water, 3 parts tricalcium phosphate, 0.02 parts sodium dodecylbenzenesulfonate, 1 part sodium chloride, 150 parts polystyrene drops, 6.4 parts n-pentane and the additives shown in the table were first Put in. The stirred mixture was heated to 110 ° C. for 2 hours and held at this temperature for 6 hours. After cooling the mixing wool, pH was adjusted to 1.4 by adding hydrochloric acid. The drops were removed by centrifugation, washed with water and dried by air flow.

B) Polymerization Experiment

In a leak-free stainless steel reactor, 150 parts fully deionized water, 0.1 parts tartrium pyrophosphate, 100 parts styrene, 7 parts pentane, 0.45 parts benzoyl peroxide 0.15 parts tert-butylperbenzoate and the amount of additives shown in the table The mixture of was heated to 90 ° C. with stirring.

After 2 hours at 90 ° C., 4 parts of a polyvinylpyrrolidone 10% concentration solution was added.

Stirring was continued for 2 hours at 90 ° C, and then for 2 hours at 100 ° C, and for 2 hours at 120 ° C.

The resulting particles with an average particle diameter of 1.1 mm were separated, dried and dried.

C) production of foam

패들 혼합기에서 03중량%의 글리세롤 모노스테레이트로 덤블링함으로써 피복시켰다. 연속적인 Rauscher 교반 예비발포기에서 스팀을 흘려줌으로써 폴리스티렌입자를 20g/ι의 부피밀도를 예비발포시키며, 24시간동안 저장한후 자동 Hofstetter 성형기에서 2.1bar 하에서 스팀으로 처리하여 용접시킴으로써 평행항 관이된 발포제품을 형성시킨다. 용접은 미국특허 제3,526,605호에서 기술된 방법에 의해 결정하였다.Polystyrene pellets containing a blowing agent obtained from A and B and having a particle fragment of 0.7 to 1.2 mm

The coating was done by dumping with 03% by weight of glycerol monosterate in a paddle mixer. By blowing steam in a continuous Rauscher stirred prefoam, the polystyrene particles are prefoamed at a bulk density of 20 g / ι, stored for 24 hours and then welded by steam treatment under 2.1 bar in an automatic Hofstetter molding machine to form parallel anti-foamed foams. Form the product. Welding was determined by the method described in US Pat. No. 3,526,605.

The results obtained are summarized in the table. In the examples, the parts are by weight.

TABLE 1

Description of the subsequent impregnation

1) h: uniform / n.h: non-uniform

2) Mixed coagulum

Table 1 (continued)

Experiment on subsequent impregnation

1) h: uniform / n.h: non-uniform

2) Mixed coagulum

TABLE 2

Description of the subsequent impregnation

1) h: uniform / n.h: non-uniform

2) Mixed coagulum

3) deformed drops

Claims (2)

(a) 3 to 15% by weight of a C ₃ -C ₈ hydrocarbon or haloalkane as a blowing agent, b) 0.005 to 0.3% by weight of resin acid, a lower ester of resin acid or (hydro) abiethylphthalei and (c A foamed styrene polymer containing from 0.001 to 0.3% by weight of polyoxyethylene nomoester or monoether and optionally (d) other conventional additives. It has a density of 0.01 to 0.05 g / cm 3 and includes (a) 0.005 to 0.3 wt% resin acid, lower ester of resin acid or (hydro) avietaphthalate and (b) 0.001 to 0.3 wt% polyoxyethylene mono Styrene polymer foam containing esters or monoethers and optionally (c) conventional additives.